Protractor



ATENT rFicE.

ABEL BUTLER, OF DAIJE, INDIANA.

PROTRACTOR. j

SPECIFICATION forming part of Letters Patent N 0. 395,875, dated January 8, 1889.

Application filed August 9, 1888.

T0 at whom it may concern:

Be it known that I, ABEL BUTLERJL citizen of the United States, residing at Dale, in the county of Spencer and State of Indiana, have invented certain new anduseful Improvements in Protractors; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the annexed drawings, making a part of this specification, and to the letters and figures of reference marked thereon.

This invent-ion relates to certain new and useful improvements in devices for laying off maps and the like; and it has for its objects to improve upon prior devices of this character and to provide a protractor which is adapted for various uses, and which in practice will be found to be very etficient and reliable, andwhich will lessen to a great extent the labor of drawing maps and the like.

The novelty resides in the peculiar cor.- struction of the device and in the combinations, arrangement, and adaptation of parts, all as more fully hereinafter described and claimed.

The invention is clearly illustrated in the accompanying drawings, which, with the letters of reference marked thereon, form a part of this specification, and in which- Figure l is a perspective view of my improved protractor. Fig. 2 is a similar view showing the parts in a different position. Fig. 3 is a vertical cross-section through the line .11.:0 of Fig.

The protractor is designed and adapted more particularly for teachers use in mapdrawing, being so arranged that the projections of the hemispheres and the grand divisions can be easily and correctly made according to any text-book.

The device may be made of any suitable 1naterial-wood, iron, or partly wood and part metal-and of any desired size.

u l u i Referring to thcdctails of the drawings by letter, A designates a section of the protractor, there being two like sections pivotally secured together, as at a, in anysuitable manner. In the drawings I have shown on one of the sections a bar, B, or, preferably, two bars-one at the top and the other underneath the section-and through the bar or thumb-nut, as shown.

Serial No. 282,386. (No model.)

bars is passed the shank of a screw, 1), which serves as a swivel on which the sections may swing to construct a larger or smaller map. This screw is provided with a thumb-nut, b, which serves to hold the parts in their adj usted positions. This portion composed of the two sections forms a semi-circle, the inner face of which is graduated into factors of three hundred and sixty degrees, while the straight-edge is also graduated, as shown. The semi-circle terminates in circular ears C, partly graduated by factors of three hundred and sixty degrees. On each end of the semicircle is also formed a graduated are, D.

E is a spring secured at one end in a suitable holder, d, which is swiveled on one of the ears of the semi-circle and designed to be held in its adjusted position by means of a On the other ear is a similar holder; but the end of. the spring is passed through a slot in this holder, and is adapted to be free to slide therein, but to be securely held in its adjusted position by tightening the thumb-screw. The holder is provided with the slot 6, above mentioned, and the spring, passing through this slot, is pressed against the car when the thu1nb-nut is tightened, thus holding it in place. \Vhen the nut is loosened, of course the spring will be free to slide in its holder. This spring should also he graduated to conform 'to the graduations of the other parts of the device.

The operation is simple and apparent. For instance, to form a hemisphere place the device tlat upon a sheet of paper, draw the pencil along the semicircle, dotting the graduations of the same, the long marks indicating the intersections of the tropics, polar circles, and every twentieth parallel, the shorter marks indicating the tenth parallels, and so on. Next turn the protractor around and draw the other side of the circle in the same manner. Now draw the equator with the back of the protractor or straight-edge and divide it off into five degrees, ten degrees, or twenty degrees, as desired. Then draw and dot the central meridian in the same way; or, if it is not desired to draw or establish the central meridian, simply dot the same. Next draw and dot the polar circles by the use of the small are at the end of the protractor.

Draw the sixt ieth parallel north and south by the are at; the 130 of the protimetor. Drnw the other parallels by means of the spring, bending it till it eovers the dots at" the eiret'nnti'erenee 11nd eentml meridians. Then tighten the spring and truee, and then turn the deviee to the eorresponding' parallel on the opposite side of the equator and draw it, 11nd so on.

The holders or zuljustlers on the ears of the semi-eirele e111] he turned till the curve heeomes t'nll enough near the poles. Then tighten the some and truee the eurves.

The partsnniyhmidjusted to draw :1 snmller 5 v sen1i-eirele,z1 graduated strnigl1t-ede'e, ears,

or larger 11111 11, 11s desired.

\Yhnt I eh1i111 11s new is l. A protruetor lernu-d ol two pan-ts hinged together and forming :1 seini-eirele, and pro videdwit l1 n11 ndjnst'zlhle spring, suhstnnt i;1l I as described.

2. \1')1'otr;1etortorn1ed ol'twopm'ts l'orniiny; :1 senli-eirele graduated as deserihed, :111d :1 spring eonneetingthe outerends ot' said sen1il eirele, suhstnntinlly 21s 11nd tor the pnr mse specified.

A protrnet'or formed with. graiiluated seini-eirele formed of two parts hinget'l together, grmlunted ores, and :11 graduated strnight-edge on the hnek ol the parts forming the seini-eirele, suhstnntialLYas deserihed.

4;. A protrnet'or eomposed of 11 graduated hinged sen1i-eirele,;1grmlunted stru igldi-ei'lge, and graduated spring, and n1z1de zldjustnhle, suhstnnt'iz'illy 21s deserifhml.

A protrnetor t'oi'ined. with :1 senIi-eirele grnduzltwl 11s desei-ihed, grzuluuted zn'es, straight-edge 11nd ears, and 11 spring; eonneeting the endsol' the seini-eirele 21nd graduated as deserihmjl. 1

(I. Aprot'rnetor formed with :1 grznlunted 11nd ares, 11 graduated spring eonneeting the ends (11' the seini-eirele, :111d swiveled holders for said spring, suhstnntiulhv 11s deserihed.

Tn testimony that I elniin the .lhovel have hereunto suhserihed |1| 1|:11ne in the present-e of two witnesses.

ABEL lll"ll1ER.

Witnesses:

MELlssA .J'. 'lFLnxnAM, J OHN J. TUBNHAM. 

